1. Field of the Invention
This invention relates to a method for the preparation of tertiary butyl alcohol (TBA) by the catalytic decomposition of tertiary butyl hydroperoxide (TBHP). More particularly, this invention relates to a method wherein a tertiary butyl hydroperoxide charge stock comprising a solution of tertiary butyl hydroperoxide dissolved in a cosolvent mixture of isobutane and tertiary butyl alcohol is brought into contact with a hydroperoxide decomposition catalyst in a reaction zone to convert the tertiary butyl hydroperoxide to peroxide decomposition products, principally tertiary butyl alcohol.
2. Prior Art
It is known to react isobutane with oxygen, either thermally or catalytically, to form a peroxidation reaction product wherein the principal peroxide that is formed is tertiary butyl hydroperoxide. It is also known to thermally or catalytically decompose the tertiary butyl hydroperoxide in a peroxide decomposition zone to form tertiary butyl alcohol. Normally, the unreacted isobutane is removed from the peroxidation reaction product so that the feedstock for the hydroperoxide decomposition zone is a debutanized peroxidation reaction product.
In the text entitled "Organic Peroxides" edited by Daniel Swern (Wiley Interscience, a Division of John Wiley & Sons, New York), in Vol. II on page 157 it is stated that the metal-ion-catalyzed decomposition of primary hydroperoxides yields mainly alcohols, aldehydes and carboxylic acids, citing as an example the decomposition of hydroxymethyl hydroperoxide with aqueous ferrous sulfate to provide formaldehyde, formic acid and water.
Quin U.S. Pat. No. 2,854,487 discloses the hydrogenation of hydrocarbon peroxides in the presence of hydrogen and palladium on activated alumina to provide carbinols.
In Massie U. S. Pat. No. 3,775,472 a process is disclosed wherein alkyl substituted aromatic hydrocarbons are oxidized to products such as aromatic alcohols, aldehydes and carboxylic acids in the presence of ruthenium compounds.
Grane U.S. Pat. No. 3,474,151 discloses that tertiary butyl alcohol starts to dehydrate at 450.degree. F. and to decompose at a "rapid rate" at temperatures above 475.degree. F. Grane discovered, however, that residual quantities of hydroperoxide contaminants present in tertiary butyl alcohol could be thermally decomposed by heating the contaminated tertiary butyl alcohol at a temperature of 375.degree. to 475.degree. F. for about 1 to 10 minutes.
Grane et al. U. S. Pat. No. 4,294,999 discloses a process wherein isobutane is oxidized in a pressured reactor in the presence of a solubilized molybdenum catalyst to provide a mixture of tertiary butyl alcohol, tertiary butyl hydroperoxide, methanol, acetone, and other oxygen-containing compounds. The tertiary butyl hydroperoxide is thermally decomposed under pressure at about 280.degree. F. to provide a tertiary butyl alcohol product containing only residual quantities of tertiary butyl hydroperoxide which are then decomposed in accordance with Grane U.S. Pat. No. 3,474,151 by heating the tertiary butyl alcohol at 375.degree. to 475.degree. for about 1 to 10 minutes. Heating tertiary butyl alcohol containing small amounts of peroxides at high temperatures for even short periods of time to remove the peroxides produces undesirable products such as isobutylene.
Grane et al. U.S. Pat. No. 4,296,262 discloses a related process wherein isobutane is reacted with oxygen in a reaction zone for a residence time of about 1 to 10 hours at a temperature of about 240.degree. to about 340.degree. F. and a pressure of about 100 to about 1000 psig. in the presence of a catalytically effective amount of a soluble molybdenum catalyst. A liquid stream comprising tertiary butyl alcohol is recovered from the reaction mixture and fed to a decomposition zone wherein the tertiary butyl hydroperoxide contained therein is decomposed by "hot aging" at 250.degree.-350.degree. F. at a pressure lower than the pressure in the oxidation zone. The tertiary butyl alcohol can be further subjected to a clean-up treatment at 375.degree.-475.degree. F. for 1 to 10 minutes. Worrell et al. in U.S. Pat. No. 4,296,263 disclose a related process wherein the feedstock is a mixture of normal butane with isobutane and wherein the oxidation catalyst is a soluble form of chromium, cobalt, nickel, manganese, molybdenum, or a mixture thereof.